Common Bean Plants Research Articles

Unveiling the Potential of Coffee Grounds, Banana Peels and Egg Shells as an Eco‐Friendly and Sustainable Fertilizer

AbstractCoffee grounds, along with other organic materials like eggshells and banana peels, offer a promising solution for improving food security. This research brings innovation to the forefront by reimagining kitchen waste as a valuable resource for sustainable agriculture, introducing a multicomponent fertilizer approach, exploring different application methods, and focusing on a staple crop, ultimately contributing to the broader discourse on food security and environmental conservation. This study evaluated the effect of coffee grounds, eggshells, and banana peels as fertilizers on the growth and germination of Phaseolus vulgaris (common bean) plants. Two types of fertilizers are prepared: a dry mixture and a wet mixture obtained by boiling the dry mixture in water for 15 min. The height of the plants is measured weekly over a period of four weeks. The results indicated that the wet fertilizer mixture is more effective in promoting plant growth than the dry mixture. Plants that received the wet fertilizer mixture exhibited a higher growth rate and reached a greater height than those that received the dry mixture. It can be concluded that the wet fertilizer mixture is more efficient in promoting the growth of Phaseolus vulgaris plants than the dry mixture.

The interplay between the inoculation of plant growth-promoting rhizobacteria and the rhizosphere microbiome and their impact on plant phenotype

Microbial inoculation stands as a pivotal strategy, fostering symbiotic relationships between beneficial microorganisms and plants, thereby enhancing nutrient uptake, bolstering resilience against environmental stressors, and ultimately promoting healthier and more productive plant growth. However, while the advantageous roles of inoculants are widely acknowledged, the precise and nuanced impacts of inoculation on the intricate interactions of the rhizosphere microbiome remain significantly underexplored. This study explores the impact of bacterial inoculation on soil properties, plant growth, and the rhizosphere microbiome. By employing various bacterial strains and a synthetic community (SynCom) as inoculants in common bean plants, the bacterial and fungal communities in the rhizosphere were assessed through 16 S rRNA and ITS gene sequencing. Concurrently, soil chemical parameters, plant traits, and gene expression were evaluated. The findings revealed that bacterial inoculation generally decreased pH and V%, while increasing H+Al and m% in the rhizosphere. It also decreased gene expression in plants related to detoxification, photosynthesis, and defense mechanisms, while enhancing bacterial diversity in the rhizosphere, potentially benefiting plant health. Specific bacterial strains showed varied impacts on rhizosphere microbiome assembly, predominantly affecting rhizospheric bacteria more than fungi, indirectly influencing soil conditions and plants. Notably, Paenibacillus polymyxa inoculation improved plant nitrogen (by 5.2%) and iron levels (by 28.1%), whereas Bacillus cereus boosted mycorrhization rates (by 70%). Additionally, inoculation led to increased complexity in network interactions within the rhizosphere (∼15%), potentially impacting plant health. Overall, the findings highlight the significant impact of introducing bacteria to the rhizosphere, enhancing nutrient availability, microbial diversity, and fostering beneficial plant-microbe interactions.

Homeopathic preparations to increase resistance and development of yield in bean (Phaseolus vulgaris) crops

The common bean (Phaseolus vulgaris) is an essential part people’s staple diet in Brazil as well as in some Latin American countries. The excessive use of agrochemical for pest and disease control negatively impacts human health, contaminates soil and water, harms biodiversity, and contributes to pest resistance. It is referred to a specific homeopathic preparation. In the context of homeopathy, the term "preparations" refers to homeopathic remedies that are created through a specific process of dilution and agitation. The use of highly diluted homeopathic preparations, which enhance the plants ability to resist diseases, represents a more sustainable and environmentally friendly alternative. In homeopathy, "Silicea" is used as a homeopathic remedy derived from silica which is not a silica in its natural form. The objective of this study was to evaluate the effect of Silicea terra and Phosphorus application in high dynamized dilutions, on morphometric and productive variables of common bean plants. Two experiments were carried out in a greenhouse and one experiment in the field, in a randomized block design for both situations. In greenhouse, the preparations were used in dynamizations 7, 12, 24, 36, 48 and 60CH (CH= Hahnemannian centesimal dilution order) and distilled water was used as control. In the field, the treatments were Phosphorus 48 and 60CH, Silicea terra 36 and 60CH, and distilled water as a control. In greenhouse, application of Silicea terra 36CH increased (p< 0.05) shoot dry biomass weight (9.78 g) and leaf dry biomass weight (5.36 g), compared to control. In the field, Silicea terra 36CH and Phosphorus 60CH increased bean productivity in relation to the control. The results indicate that homeopathic preparations had a high potential for improving development and consequently increasing yield when applied to common bean plants.

Productivity and basic indicators of common bean (haricot) modern varieties suitability for mechanized harvesting

Goal. Investigation of plants height, a lower bean attachment height, 1000 seeds weight, ripening period duration, and productivity of common bean (haricot) modern varieties, depending on cultivating technological methods.
 Methods. Field method — to determine the plants height and grain crop capacity; laboratory one — to determine the basic elements of common bean plant crop structure; statistical — for mathematical data processing by variance analysis method.
 Results. All the six common (haricot) bean varieties investigated in the research, were bushy. However, the varieties Nata and Bukovynka showed the «chick-pea» (twisted) top appearance in years with excessive humidity. The variety Slavia was characterized by the lowest height of the lower bean attachment — 8.1—8.8 cm. Other researched varieties were more technologic. Particularly, the variety Galaktyka had the lower bean attachment height 10.1—10.6 cm, Bukovynka — 10.5—11.5, Nata — 10.5—11.8, Ros’ — 11.4—12.4 cm. The lower bean elevated location of the variety Otrada (12.9—13.5 cm) allows to minimize the losses during direct combine harvesting. All the varieties investigated by us had a medium-sized seed (from 201 tо 400 g). The smallest seed was in the variety Bukovynka — 204—212.6 g. The largest 1000 seeds weight was in the variety Galaktyka — 323.5—337.9 g. All the common bean vaieties researched in the experiment, except Galaktyka, exceeded the variety Bukovynka by grain yield. Thus, on the variant without seed inoculation and using potassium humate, the variety Galaktyka grain yield made 1.33 t/hа, which was by 34.5% less, compared to the variety Bukovynka. A complex use of inoculants and potassium humate provided a significant grain yield increase of the researched common bean varieties. The maximum yield increase in the research (0.27 t/hа or 11.0%) was obtained during pre-sowing seed inoculation and two foliar feedings with potassium humate of common bean stands of the variety Otrada.
 Conclusions. All the varieties researched in the experiment are bushy, and bushy with a «chick-pea» (twisted) top and suitable for direct combine harvesting. The maximum grain yield level was provided by the following varieties: Otrada — 2.72 t/ hа; Nata — 2.65 t/hа, and Ros’ — 2.54 t/hа, during seed inoculation with biologics Rhizoactive + Rootella, complete mineral fertilizer introduction in dosage N32Р32К32, and two foliar feedings with potassium humate.

Response of common bean (Phaseolus vulgaris L.) plant to foliar spray with some growth activators

Response of common bean (Phaseolus vulgaris L.) plant to foliar spray with some growth activators

Rhizobia-legume symbiosis mediates direct and indirect interactions between plants, herbivores and their parasitoids

Microorganisms associated with plant roots significantly impact the quality and quantity of plant defences. However, the bottom-up effects of soil microbes on the aboveground multitrophic interactions remain largely under studied. To address this gap, we investigated the chemically-mediated effects of nitrogen-fixing rhizobia on legume-herbivore-parasitoid multitrophic interactions. To address this, we initially examined the cascading effects of the rhizobia bean association on herbivore caterpillars, their parasitoids, and subsequently investigated how rhizobia influence on plant volatiles and extrafloral nectar. Our goal was to understand how these plant-mediated effects can affect parasitoids. Lima bean plants (Phaseoulus lunatus) inoculated with rhizobia exhibited better growth, and the number of root nodules positively correlated with defensive cyanogenic compounds. Despite increase of these chemical defences, Spodoptera latifascia caterpillars preferred to feed and grew faster on rhizobia-inoculated plants. Moreover, the emission of plant volatiles after leaf damage showed distinct patterns between inoculation treatments, with inoculated plants producing more sesquiterpenes and benzyl nitrile than non-inoculated plants. Despite these differences, Euplectrus platyhypenae parasitoid wasps were similarly attracted to rhizobia- or no rhizobia-treated plants. Yet, the oviposition and offspring development of E. platyhypenae was better on caterpillars fed with rhizobia-inoculated plants. We additionally show that rhizobia-inoculated common bean plants (Phaseolus vulgaris) produced more extrafloral nectar, with higher hydrocarbon concentration, than non-inoculated plants. Consequently, parasitoids performed better when fed with extrafloral nectar from rhizobia-inoculated plants. While the overall effects of bean-rhizobia symbiosis on caterpillars were positive, rhizobia also indirectly benefited parasitoids through the caterpillar host, and directly through the improved production of high quality extrafloral nectar. This study underscores the importance of exploring diverse facets and chemical mechanisms that influence the dynamics between herbivores and predators. This knowledge is crucial for gaining a comprehensive understanding of the ecological implications of rhizobia symbiosis on these interactions.

Wavelength and Light Intensity Affect Macro- and Micronutrient Uptake, Stomata Number, and Plant Morphology of Common Bean (Phaseolus vulgaris L.)

It is already known that light quality and intensity have major influences on the growth, etiolation, germination, and morphology of many plant species, but there is limited information about the effect of wavelength and light intensity on nutrient absorption by plants. Therefore, this study was established to evaluate the plant growth, stomata formation, chlorophyll index, and absorption of macro- and micronutrients by common bean plants under six light treatments. The experimental design was completely randomized and consisted of six treatments: strong blue (blue LED at high light intensity); weak blue (blue LED at low light intensity); strong red (red LED at high light intensity); weak red (red LED at low light intensity; pink (combined red + blue LED), and white (combined red + white led). The stomatal density (stomata mm−2); the SPAD index; plant height (cm); root length (cm); plant dry weight (g); root dry weight (g); and the concentrations of N, S, K, Mg, Ca, B, Zn, Mn, and Fe on leaf analysis were influenced by all treatments. We found that plant photomorphogenesis is controlled not only by the wavelength, but also by the light intensity. Etiolation was observed in bean plants under blue light at low intensity, but when the same wavelength had more intensity, the etiolation did not happen, and the plant height was the same as plants under multichromatic lights (pink and white light). The smallest plants showed the largest roots, some of the highest chlorophyll contents, and some of the highest stomatal densities, and consequently, the highest dry weight, under white LED, showing that the multichromatic light at high intensity resulted in better conditions for the plants in carbon fixation. The effect of blue light on plant morphology is intensity-dependent. Plants under multichromatic light tend to have lower concentrations of N, K, Mg, and Cu in their leaves, but the final amount of these nutrients absorbed is higher because of the higher dry weight of these plants. Plants under blue light at high intensity tended to have lower concentrations of N, Cu, B, and Zn when compared to the same wavelength at low intensity, and their dry weight was not different from plants grown under pink light. New studies are needed to understand how and on what occasions intense blue light can replace red light in plant physiology.

Taxa de aplicação e pontas associados à eletrificação de gotas afetam a qualidade da pulverização em feijoeiro

ABSTRACT The objective of this work was to evaluate the application efficiency of different nozzle tips associated with increasing application rates. A field experiment was conducted in a factorial 3 × 4 randomized block design with four replicates. The first factor consisted of three types of nozzle tips (simple flat fan, hollow cone, and hollow cone with the electrification of the drops), and the second factor constituted the four application rates (50, 100, 200, and 250 L ha-1). Electrostatic technology and a hollow cone tip increased the deposited volume on leaves on the upper and medium strata of the common bean plant, regardless of the application rate used. The increase in the application rate increased the volume of spray solution captured in the upper, medium, and lower strata, the drop density, the volumetric median diameter (VMD), and the percentage of foliar coverage, regardless of the spray tip evaluated. The percentage of leaf coverage on the adaxial and abaxial leaf was not influenced by the simple fan or hollow cone spray tips, with or without the association of electrostatic technology.

Biological control of root-knot nematodes in common beans using putative nematocidal species of Trichoderma indigenous to Pakistan

ABSTRACT The putative nematocidal strains of Trichoderma for controlling root-knot nematodes were isolated from different agricultural fields in Pakistan. The Trichoderma isolates were confirmed using morphological and molecular characterisation. The root-knot nematodes were isolated from infected common bean plants Phaseolus vulgaris and identified as Meloidogyne incognita through phenotypic characteristics. Both in vitro and in vivo assays were performed. The nematocidal activity of the selected Trichoderma spp. was assessed using culture filtrate and spore suspension assays. Parameters including J2 mortality, egg hatching inhibition, root gall index, and egg mass index were calculated. The culture filtrates of T. bevicrassum strain ISO-03 caused significantly higher J2 mortality (71%) and inhibited egg hatching (68%) as compared to the activities of culture filtrates of the other two strains used in this study. The least control activity was observed in case of the culture filtrates of T. viride strain ISO-05 with 21% J2 mortality and 19% egg hatching inhibition. Similarly, the spore suspensions of T. brevicrassum ISO-03 showed the highest mortality of M. incognita juveniles (64% with respect to control) as well as the egg-hatching inhibition rates of 59%. In the in vivo study, the same strain T. bevicrassum ISO-03 significantly reduced the root galling index and egg mass indices as compared to the control. Furthermore, T. bevicrassum ISO-03 significantly promoted plant growth compared to the control. Overall, T. bevicrassum ISO-03 was identified as a potent biocontrol strain against root-knot nematodes in addition to its plant growth-promoting characteristics.

Molecular Characteristics of Bean Common Mosaic Virus Occurring in Inner Mongolia, China.

Bean common mosaic virus (BCMV) was detected on common bean (Phaseolus vulgaris) plants showing wrinkled and/or narrow leaves, curling, shrinking and chlorosis of leaves, dwarfing of plants, and mottled pods in Inner Mongolia and named BCMV-22Huhe. Its genome has a size of 10,062 bp and was deposited in GenBank under the accession number OR778613. It is closely related to BCMV-Az (GenBank accession no. KP903372, in China) in the lineage of AzBMV. A recombination event was detected for BCMV-22Huhe among the 99 BCMV isolates published in the NCBI GenBank database, showing that BCMV-CJ25 (MK069986, found in Mexico) was a potential major parent, and the minor parent is unknown. This work is the first description of the occurrence of BCMV in Inner Mongolia, China.

Impact of Chlorella vulgaris, Nannochloropsis salina, and Arthrospira platensis as bio-stimulants on common bean plant growth, yield and antioxidant capacity

The use of bio-stimulants in agriculture has emerged as a promising strategy to improve crop growth and yield. One type of bio-stimulant that has gained attention is microalgae extracts, which are known for their high metabolic activity, bioactive compounds, and ability to enhance plant growth and development. To investigate their effectiveness, a pot experiment was conducted at the Experimental Farm of Helwan University in Egypt during the 2022 season. The experiment aimed to evaluate the efficacy of Chlorella vulgaris, Nannochloropsis salina, and Arthrospira platensis (Spirulina platensis) extracts as bio-stimulants, applied through foliar spray at concentrations ranging from 0.25 to 2.0%, on common bean plants. Analysis of algal extract showed that . N. salina had the highest content of promotive growth hormones gibberellins (GA3) (74.85 ± 2.7mg100 g−1 d.wt). and auxins (IAA) (34.57 ± 2.7µg 100 g−1 d.wt.) compared to Chlorella and Arthrospira..The results revealed that the application of C. vulgaris, N. salina, and A. platensis extracts at concentrations up to 1.0% significantly improved various growth parameters, such as root, and shoot length, number of leaves and flowers per plant, leaf area, and total fresh and dry weight per plant. These extracts also positively affected yield attributes, including the number and fresh weight of pods per plant, seed index, seed yield per plant, and per feddan [a unit of land area]. Furthermore, the application of these extracts increased the chlorophyll content index with the maximum values of CCI (17.95. and 17.81%) was obtained at 0.50% N. salina, followed by 0.50% C.vulgaris. In addition to increase in the capacity of both non-enzymatic antioxidants [such as total antioxidant capacity, phenolics, and flavonoids] and enzymatic antioxidants [including catalase and ascorbic oxidase]. The most promising results were observed with the application of N. salina, and C. vulgaris extracts at a concentration of 0.5%. Additionally, the extracts significantly reduced the content of oxidative stress markers, such as malondialdehyde, percentage of electrolyte leakage, and hydrogen peroxide, in common bean plants compared to the control group. Contrarily, the measured parameters were reduced, while the levels of oxidative stress markers and some antioxidants including peroxidase, ascorbic peroxidase, superoxide dismutase, glutathione peroxidase, and glutathione transferase were increased by three algal extracts at a concentration of 2.0%, compared to control plants. Additionally, the application of these microalgae extracts improved the quality parameters, proximate composition, seed energy, and mineral contents of the harvested seeds, with the most significant positive impact was observed at 0.5% concentration of algal extract. These findings demonstrate the successful and safe utilization of extracts from C. vulgaris, N. salina, and A. platensis at concentrations up to 1.0% as bio-stimulants to enhance common bean yields and improve the nutritional quality of dried beans for consumers.

Microbial Insights into Biofortified Common Bean Cultivation

Microorganisms play a fundamental role in sustainable agriculture, and their importance in common bean (Phaseolus vulgaris) cultivation cannot be underestimated. This review article aims to comprehensively explore the diverse roles of microorganisms in sustainable biofortified common bean cultivation. Biofortification refers to the process of increasing the nutrient content in crops, which helps combat deficiencies in iron, zinc, and vitamins in the human body. Biofortified beans have better agronomic characteristics and offer higher micronutrient content compared to conventional crops. We examine the contribution of various microbial communities in nitrogen fixation, soil structure improvement, nutrient recycling, and disease suppression. Understanding the interaction between beneficial microorganisms and biofortified common bean plants enables us to develop ecologically sound and sustainable approaches to optimize crop productivity and improve nutrition and livelihoods for millions of people worldwide while reducing the environmental impact of agricultural practices.

Fostering resistance in common bean: Synergistic defense activation by Bacillus subtilis HE18 and Pseudomonas fluorescens HE22 against Pythium root rot

Root rot of common bean caused by Pythium aphanidermatum is a serious disease that causes significant losses to the production and yield of this crop. This study aimed to biocontrol the root rot disease of common bean using Bacillus subtilis HE18 and Pseudomonas fluorescens HE22 as effective bioagents and promote the growth of this plant. Using the in vitro dual culture assay, B. subtilis HE18 and P. fluorescens HE22 inhibited the radial growth of the pathogenic P. aphanidermatum by 67.95 and 48.39%, respectively. Chemical analysis of the cell-free filtrates of both bioagents using GC/MS demonstrated the production of twenty and thirteen volatile compounds by B. subtilis HE18 and P. fluorescens HE22, respectively, which may account for their significant antifungal efficacy. In the greenhouse, the application of a combination of both bio-inoculants displayed lower severity of pre- and post-emergence damping off and high plant survival, recording 10.1, 6.7, and 83.3%, respectively. The expression of the defense-related genes JERF3, GLU, and PR1, was examined in the treated plants using qPCR, where the highest upregulation levels were recorded for the infected plants that were treated with the combined biocontrol agents. Treating of the infected common bean with a combination of B. subtilis HE18 and P. fluorescens HE22 increased the activity levels of POD and PPO antioxidant enzymes and enhanced the phenol content. Combined treating of the infected plants with both bioagents increased the TSS to 14.15 °Brix, compared with the infected, untreated plants (7.05 °Brix). The dual application of both bioagents expressed a significant increment in Chl. a and b pigments, enhanced the levels of carotenoids, and increased the total pigments. Treating of the infected and control plants with both bio-inoculants caused an appreciable increment in the shoot height, root length, and shoot and dry weights, respectively. Moreover, the same treatment increased the pod weights, pod length and width, and the number of seeds pod−1, in addition to the yield plant−1. Finally, we concluded that both bioagents acted synergistically against the fungal pathogen, as they targeted multiple sites in the fungal cell and promoted the growth parameters and yields of the treated common bean plants.

Bean intercropping systems with small castor hybrids.

Research aimed at investigating the ideal plant arrangement system of common beans under intercropping with castor hybrids is necessary, as intercropping is a common practice in Brazil, and this practice affects the morphophysiological behavior of both crops. The objective of this study was to evaluate the consociation systems of common bean plants with small-sized castor hybrid, in three agricultural years, in the edaphoclimatic conditions of the Cerrado of Goiás, Brazil. In the three experiments, the randomized block design with four repetitions was used, involving the combination of five simultaneous sowing systems: beans sown on the castor row, on the inter-row, on the row + inter-row and beans and castor in monocropping. The bean cultivar used was Pérola; for castor the Agima hybrid was used. The plant height, primary yield components and the yield of the beans were evaluated, while for castor was evaluated the plant height, stem diameter, number of racemes per plant, plus the yield, in addition to the area equivalence index (AEI) to verify the efficiency of the intercropping. The arrangement of bean plants cv. Pérola on row and row + inter-row of the Agima 110204 castor hybrid provides higher yields of the legume. The yield of castor hybrids is not influenced by the common bean crop. The growing of common bean and the castor hybrid in the intercropping system is more efficient than the monocropping of both crops.

Evaluation of Enhancing Biochar and the fungus Glomus mosseae in the Growth of Common Bean, Phaseolus vulgaris infected with Rhizoctonia solani

Abed, R.M. 2024. Evaluation of Enhancing Biochar and the fungus Glomus mosseae in the Growth of Common Bean, Phaseolus vulgaris infected with Rhizoctonia solani. Arab Journal of Plant Protection, 42(2): 215-223. https://doi.org/10.22268/AJPP-001232 The possible role of biochar and its interaction with the fungus Glomus mosseae in promoting the growth of the common bean plant, Phaseolus vulgaris L., grown under biological stress of infection with the pathogenic fungus, Rhizoctonia solani was investigated. The results showed that the addition of biochar and the treatment with mycorrhizal fungus, and the interaction between them, led to a significant reduction in the seedling mortality and the severity of root rot disease of the common bean plant. The results obtained showed that the mycorrhizal traits, which included infection rate, severity of infection, and number of spores, were affected by the presence of the pathogenic fungus, as all the studied mycorrhizal traits decreased, compared to the treatment of the mycorrhizal fungus in the absence of the root rot fungus. The results obtained also showed that the decrease in the disease had a positive effect on the vegetative and root plant growth and nutrients content. The results obtained encourages the application of biochar as an alternative to chemical pesticides for the control of common bean root rot. Keywords: BioChar, common bean, Rhizoctonia solani, Glomus mosseae, mycorrhiza

Genome-wide Analysis and Functional Identification of KCS Gene Family under Drought and Salt Stresses in Phaseolus vulgaris L

β-ketoacyl-CoA synthase (KCS) is an important enzyme that catalyzes the biosynthesis of very-long-chain fatty acids (VLCFAs). In this study, the genome-wide analysis and functional characterization of the KCS gene family members in common bean (Phaseolus vulgaris L.) plants were conducted, and the response of the identified gene family to abiotic stresses was evaluated. In this study, 19 KCS genes were identified and characterized in the P. vulgaris genome. The molecular weights of these KCS proteins ranged from 49.14 kDa to 60.57 kDa, their amino acid lengths varied from 437 to 534, and their pI values ranged from 8.81 to 9.47, indicating a basic nature. Segmental and tandem duplications were observed in the Pvul-KCS gene family. Phylogenetic analysis revealed that Pvul-KCS proteins clustered into three main groups with Arabidopsis thaliana and Glycine max species. Comparative mapping analysis was also conducted with A. thaliana and G. max. Expression profile comparisons indicated that these genes had different expression levels in common bean varieties and played a role in the plant’s response to biotic and abiotic stresses. This study provides important insights into the biological functions of KCS genes in Phaseolus vulgaris and offers valuable information for improving drought and salt stress tolerance in common beans.

Bacterial Communities in the Rhizosphere of Common Bean Plants (Phaseolus vulgaris L.) Grown in an Arable Soil Amended with TiO2 Nanoparticles

The use of nanoparticles, such as titanium dioxide (TiO2-NPs), has increased substantially over the years. Some of them will end up in the soil, where their effect on plants and the soil bacterial community needs to be studied to determine their possible environmental risks. In this paper, beans (Phaseolus vulgaris L.) were cultivated in soil with 0, 150, or 300 mg TiO2-NPs kg−1. Plant development, nodule formation, chlorophyl content, and the bacterial community were monitored in uncultivated, non-rhizosphere, and rhizosphere soils. TiO2-NPs did not affect the beans’ growth and their chlorophyl content, but they did increase bacterial diversity and had a significant effect on the bacterial community structure in the rhizosphere, but not in the bulk and non-rhizosphere soil. Although the relative abundance of most bacterial groups varied with the TiO2-NP application rate, the cultivation of the bean plants, or the exposure time, that of Acidobacteria decreased, while that of Planctomycetes increased in the TiO2-NP-amended soil. Many bacterial groups were affected by the cultivation of the bean plants, i.e., the relative abundance of Acidobacteria, Gemmatimonadetes, Deltaproteobacteria, and Firmicutes mostly decreased in the rhizosphere independent of the application of TiO2-NPs or the time of exposure, while most groups belonging to Actinobacteria, Bacteroidetes, Rhizobiaceae, Phyllobacteriaceae, and Sphingomonadaceae were enriched.

Xanthomonas species causing leaf blight on eucalypt plants in Brazil and transfer of Xanthomonas axonopodis pv. eucalyptorum to Xanthomonas citri pv. eucalyptorum comb. nov.

AbstractOutbreaks of bacterial leaf blight (BLB) frequently affect eucalypt plants under nursery and field conditions in several countries. Although research has been conducted to unveil the causal agent, different bacterial species have been associated with similar disease symptoms in different countries. In order to determine the causal agent of BLB in Brazil, a survey was conducted in nine states to recover bacterial isolates from eucalypt plants exhibiting typical BLB symptoms. A total of 41 yellow‐colony isolates with varying aggressiveness towards a susceptible eucalypt clone were obtained, with 16S rDNA sequences indicating that they belong to the Xanthomonas genus. Rep‐PCR analysis separated the Xanthomonas population affecting eucalypt into six distinct groups revealing its high genetic diversity. The same population formed three clusters together with reference strains of X. citri, X. euvesicatoria and X. phaseoli in a phylogenetic tree constructed with partial dnaK, fyuA, gyrB and rpoD gene sequences. Clustering in the phylogenetic tree was clearly related to grouping based on rep‐PCR. Genome sequence comparisons of representative eucalypt isolates with type strains of validly published Xanthomonas species confirmed that the population consisted of X. citri, X. euvesicatoria and X. phaseoli. Inoculation of tomato, common bean, castor bean and eucalypt plants showed that the representative eucalypt isolates can cause disease in these plant species. Based on the results, the transfer of Xanthomonas axonopodis pv. eucalyptorum to Xanthomonas citri is proposed. These results are relevant for eucalypt BLB management under nursery and field conditions, including selection and deployment of effective plant resistance.

Effect of Gamma-Irradiated Ceramic Wastewater Sludge on Photosynthetic Pigments of Phaseolus Vulgaris L. (Cv. Valentino and Cv. Nebraska) Plants

The common bean plant is a highly polymorphic species, annual herb, erect and bushy, 20–60 cm tall, or twining with stems 2–3 m long, with a taproot and nitrogen nodules which the bacteria could convert nitrogen gas and stores it in the common bean plant roots. Leaves are alternate, green, or purple, trifoliolate, stipulate, petiolate, markedly pulvinus at base; leaflets ovate, entire; acuminate, 6–15 cm long, 3–11 cm wide. Many soils have been contaminated with several pollutants, mostly arising from wastes of human activities such as the use of pesticides, sewer sludge, mining and smelting sources, radioactive substances, and industrial dischargers. These different contaminants can degrade the soil and cause a negative impact on the plant due to disturbing nutrient cycling within ecosystems and subsequently human health. This study aimed to elucidate the mechanism by which the plant may cope with heavy metals stress represented in this study in the form of industrial ceramic wastewater sludge. And, evaluating the role of gamma radiation on ceramic wastewater sludge, could reduce the percentage of the endogenous levels of heavy metals in ceramic sludge. This study investigates the influence of Photosynthetic pigments of the two common bean cultivars Valentino and Nebraska which are grown in light soil clay/sand (1:1) incorporated with ceramic-wastewater sludge (CWWS) non-irradiated (1% and 2%) and gamma-irradiated (2.5 kGy and 10 kGy) for 30 days. The application of non-irradiated CWWS induced an elevation in the contents of chlorophylls a, b, and carotenoids in the two cultivars while a reverse trend was observed in the leaves of both cultivars treated with gamma irradiated CWWS.

Silicon (Si) mitigates the negative effects of iron deficiency in common bean (Phaseolus vulgaris L.) by improving photosystem activities and nutritional status

Silicon (Si) is the second most abundant element in the Earth's crust after oxygen. Its beneficial impact on crop development and yield, particularly under stressful conditions such as iron (Fe) deficiency, has been well documented. Fe deficiency is a critical constraint that limits crop production globally. The objective of this study was to investigate the effects of silicon (Na2SiO3) on common bean (Phaseolus vulgaris L. ‘Coco Rose’ variety) under iron-deficient conditions. The common bean plants were subjected to six treatments, which included three sufficient iron treatments (50 μM Fe) each paired with three varying silicon concentrations (0, 0.25, and 0.5 mM Si), and three iron-deficient treatments (0.1 μM Fe) each associated with the same silicon concentrations (0, 0.25, and 0.5 mM Si). The results indicate that iron deficiency had a negative impact on almost all the measured parameters. However, under silicon treatments, especially with 0.5 mM Si, the depressive effects of iron deficiency were significantly mitigated. The addition of 0.5 mM Si alleviated leaf chlorosis and improved biomass production, nutritional status, photosynthetic pigment content, photosynthetic gas exchange, and photosystem (PSI and PSII) activities. Interestingly, a greater beneficial effect of silicon was observed on PSII compared to PSI. This was accompanied by a significant augmentation in leaf iron concentration by 42%. Therefore, by enhancing the photosystem activities and nutritional status, among other mechanisms, silicon is capable of mitigating the adverse effects of iron-deficient conditions, making it a successful and effective solution to cope with this nutritional stress.